RESUMEN
DNA barcoding can be an effective tool for fast and accurate species-level identification based on sequencing of the mitochondrial cytochrome c oxidase subunit (COI) gene. The diversity of this fragment can be used to estimate the richness of the respective species. In this study, we explored the use of DNA barcoding in a group of ornamental freshwater fish of the genus Hyphessobrycon. We sequenced the COI from 10 species of Hyphessobrycon belonging to the "Rosy Tetra Clade" collected from the Amazon and Negro River basins and combined our results with published data. The average conspecific and congeneric Kimura 2-parameter distances were 2.3% and 19.3%, respectively. Six of the 10 species were easily distinguishable by DNA barcoding (H. bentosi, H. copelandi, H. eques, H. epicharis, H. pulchrippinis, and H. sweglesi), whereas the remaining species (H. erythrostigma, H. pyrrhonotus, H. rosaceus and H. socolofi) lacked reciprocal monophyly. Although the COI gene was not fully diagnostic, the discovery of distinct evolutionary units in certain Hyphessobrycon species under the same specific epithet as well as haplotype sharing between different species suggest that DNA barcoding is useful for species identification in this speciose genus.